After a two-week delay, Apple has finally launched its music matching service, iTunes Match, although due to copyright issues we are unlikely to see it here.
iTunes Match is a highly anticipated feature of iTunes 10.5.1, which was released overnight. The service scans a user’s music library, matches tracks copied from CDs or other sources (such as illegal downloads) with the 18 million tracks in the iTunes Store, and allows the user to access those tracks from multiple sources via iCloud.
Tracks are accessed at 256KBps AAC DRM-free quality, even if the copy in the user's library is of a lower quality.
Tracks not matched to titles in the iTunes Store, such as those by indie artists, can also be uploaded, to a maximum of 25,000.
The service costs US$24.99 per year, but is unlikely to extend outside the US, as that would require Apple to negotiate deals with each of the music labels for each additional country.
You can still download iTunes 10.5.1 here.